Blast furnace sealing apparatus



Oct. 13, 1964 5 Sheets-Sheet 1 Filed July 20, 196] 4 N2 1 n ma mm m n mm a g 2 a, v 4 w a KN @N J |l|l|.|. Wk 1\ kw MN gw WW /I Y W\ k Km NW uQ H \ww UN WNW j w @NN wwl QNN N m o. w W MN Nw NN\.W Sn \m W K o N NWQR mw Oct. 1 3,- 1964 w. E. SLAGLEY, JR 7 BLAST FURNACE SEALINGAPPARATUS 5 Sheets-Sheet 2 Filed July 20, 1961 Oct. 1.3, 1964 w. E.SLAGLEY, JR 3,152,703

BLAST FURNACE SEALING APPARATUS IN VEN TOR.

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BLAST FURNACE SEALING APPARATUS Filed July 20. 1961 5 Sheets -Sheet 4 W.E. SLAGLEY, JR

BLAST FURNACE SEALING APPARATUS Oct. 13, 1964 Fiied July 20. 1961 5Sheets-Sheet 5 United States Patent 3,152,703 BLAST FAQE EALINGAPPARATUS William E. Slagley, .lr., East Chicago, Ind, assignor to- Thisinvention relates to blast furnaces and deals primarily with sealstherefor and a method of operation which are particularly useful inblast furnaces operating at high top pressures.

Blast furnaces have for many years been operated at what is called inthe art as normal pressures. These pressures are in the order of two tothree pounds per square inch (gauge). This is the normal back-pressurecaused by the piping in the take-offs, distribution mains, and the gascleaning facilities. Prior art types of seals usable for these normalpressures are not satisfactory as pressures increase. A development inblast furnace practice in recent years is high top-pressure operation.Here a restriction is placed in the gas line leaving the furnace, and aback-pressure is deliberately imposed on the furnace. This increases theaverage furnace pressure and results in higher furnace production, lowerdust rates, better coke rates, and so forth. In practice, at the presenttime, it is desired to achieve ten to fifteen pounds per square inch(gauge) top-pressure. Indications are that improved operations willresult at top pressures up to forty pounds per square inch (gauge).Numerous furnace improvements have been made to increase the toppressure. For example, furnace and gas cleaning facilities can bereinforced, blowers of greater capacities can be installed andequalizing and relief systems can be added so that the pressure betweenthe bells can be equalized and the bells operated. In spite of theseimprovements, continued operation at these pressures has not beenpractical under normal conditions and primarily because of excessiveleakage of blast furnace gases at the bell seats and at the distributorseal. A bell seat that has an expected life of six to seven years at twoto three pounds per square inch (gauge) pressure is reduced to onlyabout two years at ten to twelve pounds per square inch (gauge)pressure, not to speak of the extremely short life of the seats at theproposed higher pressures of thirty to forty pounds per square inch(gauge).

The basis of this invention is the provision of an elastic or resilientseal that is disposed between the surfaces to be sealed, namely, thesurfaces between the conventional hopper and its associated conventionalbell, and between the hopper which can be of the distributing type andother blast furnace structure. It is an important feature of theinvention that conventional blast furnaces can be easily andeconomically equipped with the seals of the present invention.

It is a feature of the invention that when the blast furnace charge isbeing discharged from the hopper that the seal is retracted out of thepath of the blast furnace charge. The seal always contacts the bellsurface in a normal direction when in the sealing position and the bellnever scuffs or rubs the surface of the seal to cause wear.

The elastomer seal should be heat-resistant and water-.and-air-impervious at normal operating temperatures.

Elastomers such as vinylidene fluoride-hexafluoropropylene typecopolymers are usable, such as described in Industrial and EngineeringChemistry, vol. 49, page 1687, October 1957; and Report No. 58-3, May1958, by Moran and Eubank, entitled Viton A and Viton A-HV, E. I. duPont de Nemours & Co., Inc.

Particularly outstanding results are obtainable with a heat-stableelastomer product of the foregoing type and "ice composition which isproduced by E. I. du Pont de Nemours & Co., Inc., and sold under thenames Viton A-HV and Viton A.

The elastomer seal in use is always being cooled by a circulating mediumwhich also functions to activate and deactivate the seal into and out ofsealing contact between the hopper and the bell, and between thestructure of the blast furnace and the distributing hopper.

The seal here described is one which is usable at all normal furnaceoperating temperatures and even higher without damage to the elastomer.Cooling fluid, preferably oil, is supplied internally to activate anddeactivate the seal. This keeps the outside of the elastomer seal at areduced temperature, which normally does not exceed degrees F. Thefurnace temperature at the location of the seal is controlled, accordingto preferred present operating practice, to hold its optimum temperaturebelow that at which the elastomer is usable. This is done by eitherkeeping the furnace charged or by wetting the blast furnace charge, forexample with water.

The seal is a strip-like, flexible, resiliently deformable member havingone large-area surface disposed toward the hopper and another large-areasurface, opposite the one large-area surface, disposed toward the bell.

Although seals are illustrated herein as disposed between both the upperhopper and upper bell and the lower hopper and the lower bell,satisfactory results are obtainable with a seal only between the lowerhopper and the lower bell.

In the diagrammatic drawings:

FIGURE 1 is an elevational view shown mainly in cross-section of theupper portion of a blast furnace equipped with the seals of theinvention;

FIGURE 2 is a cross-sectional elevational view of the novel sealdisposed between the lower hopper and the lower bell;

FIGURE 3 is a cross-sectional elevational view of a portion of the lowerhopper and the lower bell showing the seal in sealing contacttherebetween;

FIGURE 4 is an elevational view, partly in cross-section, showing theseal extending circumferentially around the lower portion of the lowerhopper;

FIGURE 5 is a cross-sectional view of a modified form of the inventionshown in FIGURES 2, 3 and 4;

FIGURE 6 is a cross-sectional elevational view of a portion of thedistributor seal of the invention;

FIGURE 7 is a schematic view of the fluid system of the invention; and

- FIGURE 8 is a detailed elevational view of the upper hopper and upperbell, and associated structure.

In the illustrative embodiment shown in FIGURE 1 of the drawings, thereis shown the upper portion of a blast furnace 10, which in the presentembodiment is of the double bell and hopper type. The blast furnace It)includes closure means in the form of a small upper bell 11 which isadapted to move vertically into and out of seating contact with itsassociated distributing upper hopper 12, the form of which will later bediscussed in further detail. The small bell 11 is suitably mounted forvertical movement and is supported by a bell rod 13 which is connectedat its upper end to a bell beam 14 having a counter-weight 15.

The large lower bell 16 is adapted to move into and out of seatingcontact with its associated large lower hopper 17. The large lower bell16 is mounted for vertical movement and is supported by a bell rod 18which travels within bell rod 13 and which is connected to a bell beam19 having a counterweight 20. Both bell beam 14 and bell beam 19 aremounted for pivotal movement on a common support member 21. The blastfurnace charge is received into a chute 21a which permits the same to 3fall into the small hopper 12. When the small bell 11 is moved out ofseating contact with the hopper 12, the

charge is permitted to fall into the large hopper 17. From the largehopper 17 the material is subsequently caused to fall directly into theremainder of the blast furnace when the bell 16 is moved out of seatingcontact with the hopper 17. A drive mechanism 22 is employed to rotatethe upper hopper 12 to position the charge therein for even distributionon the lower bell before dumping the lower hopper 17.

The seals of the present invention include a seal 23 between the upperclosure structure 24 of the blast furnace 10 and the hopper 12, a sealdiagrammatically indicated at 25 disposed between the small upper bell11 and the upper hopper 12, and a seal 26 between the lower bell 16 andthe lower hopper 17. These seals function to prevent the blast furnacegases from escaping from the inside of the blast furnace to the outsidethereof. The seals 25 and 26 can take the forms shown in FIGURES 2, 3, 4and 5, while the seal 24 can take the form the details of which areshown in FIGURE 6.

Although in the description of FIGURES 2, 3, 4 and the lower hopper 17and the structure with which it is associated are referred to, thedescription applies equally to the structure of the small upper hopper12 and the structure with which it is associated, that is, the sealindicated generally at 25 and the seal indicated generally at 26 areconstructed alike.

Referring now to FIGURE 2 of the drawings, there is shown a conduit 27and a conduit 28, which respectively lead into and out of a chamber 29defined by the lower portion of the hopper 17 and by the elastomer seal30. As an alternative construction, conduits 27a and 28a are shown asforming a part of the hopper in place of conduits 27 and 28. The lowerportion of the hopper 17 is provided with a seat 31 which permits thebell 16 to move into and out of seating contact with the hopper 17 whenthe bell 16 is moved vertically upward and downward. The seat 31 has arecess 32 formed therein which extends around the circumference of thehopper 17. The elastomer seal 30 is retained at its marginal edgeswithin the recess 32 by an adhesive material 33 between the seal 30 andthe hopper 17, as well as by a pair of opposed retaining rings 34.Threaded fasteners 35 pass through each of the opposed retaining rings34 and the elastomer seal at is marginal edges and are threaded into thehopper 17. Upon tightening the threaded fasteners 35 the re tainingrings 34 are urged into ever tighter contact with the marginal edges ofthe elastomer seal 30. A weldment 34a is provided between each of theretaining rings 34 and the hopper 17. i

It is noted in FIGURE 3 that the seal 30 is shown in its sealingposition by solid lines and in its unsealing position by broken lines,while in FIGURE 5, the seal 30 is shown in its sealing position bybroken lines and in its unsealing position by solid lines. The fluidwhich is used in the system shown in FIGURE 7, to be described later,upon being forced into the conduit 27 and in turn into the chamber 29,causes the elastomer seal 30 to move out of the recess and into sealingcontact with the bell 16 after the bell has been moved into seatingcontact with the hopper 17. When it is desired to release the blastfurnace charge contained in the hopper 17, the fluid pressure is firstremoved by causing more of the fluid to pass out of the chamber 29 intothe conduit 28. The seal then, due to its inherent resilient character,is caused thereby to move into the position shown in FIG- URE 5. Whenthe bell 16 is lowered vertically, the blast furnace charge passesbetween the seat 31 of the hopper 17 and the bell 16. Since the seal 30is out of the path of the blast furnace charge, no scufling or rubbingof the seal results.

It should be noted that due to the construction of the seal of theinvention, the surface to be sealed need not be clean or smooth. Thewide coverage of the seal due to the large-area surfaces thereof and theeven seal pressure which is exerted by the fluid cause the seal 30 tosurround and engulf any materials lodged between the seal 3d and thesurface of the bell 16. The flexing of the elastomer seal at each cyclewill serve to make it selfcleaning.

A seal generally indicated at 23 in FIGURE 6 of the drawings has beendevised in order to prevent the blast furnace gases in the chamberbetween the upper hopper 12 and the lower hopper 17 from passing betweenthe structure 24 of the blast furnace and the distributing hopper 12 tothe outside of the blast furnace. The upper hopper 12 is of therevolving or distributing type which is caused to be rotated at definiteintervals by conventional structure indicated schematically at 22. Thehopper 12 has a rib 37 suitably sealed and secured thereto as bywelding. The rib 37 contains a seat 38 which extends around thecircumference of the hopper 12. A seal 39 is secured to a ring 41) whichlikewise extends circumferentially around the upper hopper 12. Amanifold 41 is defined by the ring 4-11 and by the elastomer seal 39. Aconduit 411a conducts the seal activating fluid from a system like andin parallel with the system shown in FIGURE 7 into the manifold 41}. Anadhesive 42 and retaining rings 43 retain the elastomer seal 39 at itsmarginal edges. A plurality of threaded fasteners 44 pass through theretaining rings 43 and the marginal edges of the seal 39 and arethreaded into the ring 41). The fluid under pressure enters the chamber41 and causes the elastomer seal 39 to be moved into seating contactwith the web 38. It is to be understood, of course, that although a rib37 having a seat 38 is illustrated, the seal 39 can be made to be movedinto sealing contact with the hopper 12 directly, if desired. Aplurality of seals 45 form part of conventional sealing structure in usetoday. They need not be eliminated in order to practice the invention.

In the modification of FIGURE 5, one of the retaining rings 43a isdisposed at the extreme lower end of the hopper 17. This embodiment isespecially useful where a very wide seal is required. Weldments 34b areprovided between the retaining rings 43 and 43a and the hopper 17. Anadhesive 42a aids in sealing the elastomer seal 30a to the hopper.

Referring now to FIGURE 8 of the drawings, the drive mechanism 22 fordriving the upper hopper 12 is shown as containing a motor 22a and agear reducer 22b suitably mounted on the upper portion of the blastfurnace 10 by brackets 220. A drive shaft 22d extending from the rearreducer 22b has fixedly mounted thereon a pinion gear 46 which mesheswith a gear 4.6a which is fixedly attached to the outer portion of thehopper 12. The motor 22a is operated intermittently to position thecharge in hopper 17 for even distribution on the lower bell.

A conduit 47 conducts the seal activating fluid from a system like andin parallel with the system shown in FIG- URE 7 into a manifold 48formed in a collar 49 in the upper portion of the blast furnace 10. Themanifold 48 extends circumferentially around the hopper 12 and leadsinto a conduit 47a, through which the fluid is discharged. The collar 49is tapered to form a bearing seat for the hopper 12. Suitable fluidseals 49a are provided between the collar 4-9 and the hopper 12 toprevent the escape of the seal activating fluid.

Where the upper hopper is of a fixed or non-rotatable type, the smallupper bell and hopper are a duplicate of the lower bell and hopper shownin FIGURES 2-5, inclusive.

The fluid system, designated generally at 50 in FIG- URE 7, can activateand deactivate the seal 30 of the invention. The hopper and the seal,for example, the lower hopper 17 and the lower bell 16 are shownschematically in conjunction with the fluid system 50'. The systemcomprises a fluid pump 51 having electrical leads 52 leading theretofrom a suitable source. The pump 51 draws the fluid which it is adaptedto pump from a sump 53 through a conduit 54. A conduit 55 leads from thepump 51 into the chamber 32 which extends around the circumference ofthe hopper. A conduit 56 leads from the opposite side of the passage 32into both of conduits 57 and 58. A valve 59, preferably of the solenoidtype, is disposed along the conduit 57. Electrical leads 60 lead to thesolenoid valve from a switch 61 which is contacted by the end of thebell beam 19. When the bell beam 19 is in the position shown in FIGURE1, then the valve 59 is in its closed position. When the bell beam 19 ispivoted counter-clockwise from the position shown in FIGURE 1, theswitch 61 is operated to energize the valve 59 into its opened position.

Similar switches 61a and 6112 are associated with the upper bell 11 andthe revolving distributor hopper 12, respectively. A cam 610 on therevolving hopper 12 actuates the switch 61b. A switch 62 is provided inleads 62a to provide for manual operation of the solenoid valve 59. Inthe event the system is manually operated, no electrical energy issupplied to the valve 59 through the leads 60. Each of these switches61a and 61b is provided with a system (not shown) like and in parallelwith the system of FIGURE 7. Parallel systems are required since, forexample, the lower bell 16 is not operated at the same time as is theupper bell 11.

The conduit 58 contains restriction orifices 63 which maintain thepressure in the system when the valve 59 is in the closed position. Theorifices can be exchanged for orifices of different sizes (not shown) sothat the fluid pressure in the chamber 32 can be adjusted. The conduits57 and 58 lead into a conduit 64- Which leads into a cooling apparatus65. The cooling apparatus 65 serves to cool the fluid which has passedthereto from the passage 32 in the blast furnace hopper 17. A conduit 66leads from the cooling apparatus 65 into the sump 53, wherefrom it isconstantly being drawn by the pump 51. It is seen that the sump 53always contains cool fluid. The cool fluid takes on heat energy from theseal when it comes into contact therewith and hence extends itslife.

In order that the cooled fluid of the system will not be unduly warmedby the heat in the blast furnace, refractory material 70 and 71 is castaround the ends of the hopper and the bell, respectively. Anchor wires72 and 73 in the refractory materials 70 and 71 reinforce the same.

For the sake of clarity, the operation of the system illustrated inFIGURE 7 and the method of the invention will be described. Assumingthat the hopper 17 has just discharged its blast furnace charge, thebell 16 is moved vertically upward until it comes into seating contactwith the hopper 17. The valve 59 is then closed either automatically ormanually so that the fluid is caused to flow through the conduit 53. Dueto the restriction orifices 63 in the conduit 58, until suflicientpressure is built up in conduit 55, the passage 32, conduit 56, and soforth, less fluid will pass through orifices 63 than is being pumped bythe pump 51. When equilibrium is reached between the amount of fluidpumped by the pump 51 and that which passes through the orifices 63, thepressure is constant and at a maximum. The components of the system areso sized that the pressure is built up rapidly so that sealing iseffective between the hopper and the bell a short time after the valve59 is closed. The hopper then receives a blast furnace charge and whenit is desired to drop the charge the valve 59 is opened whereupon fluidflow through the system increases and the pressure in the chamber 32falls rapidly. When the pressure drops, the seal, due to its resiliencyand higher furnace pressure, assumes the unsealing position shown, forexample, in FIGURE 5 by the solid lines. The bell 16 is then lowered outof seating contact with the hopper 17, whereupon the charge isdischarged. It will be noted that in the unsealing position the seal isout of the path of the blast furnace charge when the charge isdischarged from the hopper. Increased flow of cooling fluid through theseal and the rest of the system of FIG. 7 is important when the bell isopen because this is the time when the seal is exposed to the most heatand to the highest temperatures. After the charge has been discharged,the bell 16 is again moved into seating contact with the hopper 17, andthe method is repeated. The seal can be flexed one or more times at theend of each cycle in order to clean it. This is accomplished by openingand closing the valve 59 one or more times, either by a suitable timer(not shown) along leads 69 or manually by the operation of the switch62.

The method is similar with respect to the seal indicated at 23. The onlydifference is that instead of the CIQSHIC structure 24 moving toward andaway from the hopper 12 as does the bell 11, the hopper 12 rotates withrespect to the closure structure 24. When the hopper 12 has been rotatedinto the seating position, the rotation of which has caused distributionof the charge around its circumference, the seal can be activated intothe position shown by the broken lines in FIGURE 6. Shortly before thehopper is to be rotated out of the seating position, the seal isdeactivated.

The fluid employed by the system can be either a liquid or a gas. Liquidis preferable, because, due to its incompressibility, fast pressurechanges are made possible, and a liquid provides better cooling of theelastomer seal. The liquid preferably employed is a fire-resistant oil,or, in some cases, water.

The above-described embodiments being exemplary only, it will beunderstood that the present invention comprehends organizationsdiffering in form or detail from the presently described embodiments.Accordingly, the invention is not to be considered as limited save as isconsonant with the scope of the following claims.

What is claimed is:

1. In a blast furnace:

hopper means, located at the top of said furnace, for

containing a blast furnace charge, said hopper means having a loweropening;

closure means at the bottom of said hopper means;

means mounting said closure means for vertical movement between an openlower position, in which said hopper means is in communication with alower portion of said furnace and said charge is permitted to descendfrom said hopper means toward said lower furnace portion, and an upperposition for closing said lower opening of the hopper means;

means for moving said closure means between said lower and upperpositions thereof;

flexible, resiliently deformable sealing means located between saidhopper means and said closure means when the latter is in an upperposition;

said sealing means having a first surface, with at least a portionthereof facing said closure means, and a second surface with at least aportion thereof facing said hopper means;

means mounting said sealing means to said hopper means for flexingmovement of said sealing means between a sealing first position, inwhich the sealing means extends toward the path of said descendingcharge and said portion of said first surface sealingly engages anadjacent surface of said closure means, and a non-sealing, retractedsecond position located outside said path of the descending charge;

means for flowing a fluid along said second surface;

and means for pressurizing said fluid, to move said sealing means fromsaid second position to said first position thereof, and fordepressurizing said fluid to increase the flow of fluid and retract saidsealing means to its second position.

2. In a blast furnace as recited in claim 1 wherein said last-recitedmeans comprises:

means for pressurizing said fluid when said closure means is in an upperclosed position, and for depressurizing said fluid when the closuremeans moves toward its open lower position.

3. In a blast furnace as recited in claim 1 wherein:

said closure means comprises a bell movable between a lower firstposition and an upper second position;

said hopper means comprising means for seating said bell when the latteris in its second position;

said seating means including a surface recess encircling said bell andhaving an opening facing the interior of said hopper means; 1

said sealing means comprising a strip-like member with said secondsurface being a large-area surface overlying the entire recess openingwhen the sealing means is in both of its positions to close the recessopening and define, together with said recess, a fluid-tight chamber;

said first surface on the sealing means being a largearea surface,opposite said second large-area surface for engaging an adjacent surfaceof said bell;

said means for moving and retracting the sealing means including meansfor introducing a fluid into said chamber and means for withdrawing afluid from said chamber.

4. In a blast furnace as recited in claim 1 wherein:

said sealing means comprises a strip-like member composed of anon-metallic material which is heatresistant and impervious to water andgas at the normal operating temperatures in that part of the furnace inwhich said sealing means is located.

5. In a blast furnace as recited in claim 1 and cornprising:

structure surrounding and enclosing said hopper means;

means mounting said hopper means for rotation about a vertical axis;

means actuable for imparting rotation to said hopper means;

flexible, resiliently deformable second sealing means located betweensaid structure and said hopper means;

said second sealing means having a first surface, with at least aportion thereof facing said hopper means, and a second surface with atleast a portion thereof facing said structure;

means mounting said second sealing means to said structure for flexingmovement of said second sealing means between a first position in whichsaid portion of said first surface is in sealing engagement with saidhopper, and a disengaged second position;

means for flowing a fluid along said second surface of the secondsealing means;

and means for pressurizing said fluid to move said second sealing meansfrom said second position to said first position thereof, and fordepressurizing said fluid to increase the flow of fluid and retract saidsecond sealing means to its second position.

6. In a blast furnace:

hopper means;

structure surrounding and enclosing said hopper means;

means mounting said hopper means for rotation about a vertical axis;

means actuable for imparting rotation to said hopper mean-s;

flexible, resiliently deformable sealing means located between saidstructure and said hopper means;

said sealing means having a first surface, with at least a portionthereof facing said hopper means, and a second surface with at least aportion thereof facing said structure;

means mounting said sealing means to said structure for flexing movementof said sealing means between a first position, which said portion ofsaid first surface is in sealing engagement with said hopper means, anda disengaged second position;

means for flowing a fluid along said second surface;

and means for pressurizing said fluid to move said sealing means fromsaid second position to said first position thereof, and fordepressurizing s-aid fluid to increase the flow of fluid and retractsaid sealing means to its second position.

7. In a blast furnace as recited in claim 6 wherein:

said structure has an interior surface recess facing the hopper;

said sealing means comprises a strip-like member with said secondsurface being a large-area surface overlying the entire recess openingwhen the sealing means is in both of its locations to close the recessopening and define, together with said recess, a fluid-tight chamber;

said first surface on the sealing means being a largearea surface,opposite said second large-area surface, for engaging an adjacentsurface of said hopper means;

said means for moving and retracting the sealing means including meansfor introducing a fluid intosaid chamber and means for withdrawing afluid from said chamber.

8. In a blast furnace as recited inclaim 6 wherein said last-recitedmeans comprises:

means for pressurizing said fluid when the hopper means is stationary,and for depressurizing said fluid when said rotation-imparting means isactuated.

References Cited in the file of this patent UNITED STATES PATENTS2,486,312 Mohr et al. Oct. 25, 1949 2,516,190 Dougherty et al. July 25,1950 2,599,334 Latham June 3, 1952 3,042,360 Sneddon July 3, 1962 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0. 3 152 703October 13 1964 William E, Slagley Jr.

It is hereby certified. that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3 line 46 for "is" read its column 4L line 49 for "rear" readgear column 8 line 16 before "which" insert in Signed and sealed this26th day of January 1965.,

(SEAL) Attest:

I ERNEST W. SWIDER' EDWARD J. BRENNER eating Officer Commissioner ofPatents

1. IN A BLAST FURNACE: HOPPER MEANS, LOCATED AT THE TOP OF SAID FURNACE,FOR CONTAINING A BLAST FURNACE CHARGE, SAID HOPPER MEANS HAVING A LOWEROPENING; CLOSURE MEANS AT THE BOTTOM OF SAID HOPPER MEANS; MEANSMOUNTING SAID CLOSURE MEANS FOR VERTICAL MOVEMENT BETWEEN AN OPEN LOWERPOSITION, IN WHICH SAID HOPPER MEANS IS IN COMMUNICATION WITH A LOWERPORTION OF SAID FURNACE AND SAID CHARGE IS PERMITTED TO DESCEND FROMSAID HOPPER MEANS TOWARD SAID LOWER FURNACE PORTION, AND AN UPPERPOSITION FOR CLOSING SAID LOWER OPENING OF THE HOPPER MEANS; MEANS FORMOVING SAID CLOSURE MEANS BETWEEN SAID LOWER AND UPPER POSITIONSTHEREOF; FLEXIBLE, RESILIENTLY DEFORMABLE SEALING MEANS LOCATED BETWEENSAID HOPPER MEANS AND SAID CLOSURE MEANS WHEN THE LATTER IS IN AN UPPERPOSITION; SAID SEALING MEANS HAVING A FIRST SURFACE, WITH AT LEAST APORTION THEREOF FACING SAID CLOSURE MEANS, AND A SECOND SURFACE WITH ATLEAST A PORTION THEREOF FACING SAID HOPPER MEANS;